ABSTRACT This study investigates the feasibility of low-grade hard asphalt in high-temperature regions. We conducted an analysis of the high-temperature rheological properties of asphalt before and after short-term and long-term aging using the dynamic shear rheological (DSR) test and multi-stress creep recovery (MSCR) test. Additionally, the road performance of the asphalt mixture was studied by rutting test and low temperature beam bending test. The results indicate that the 30# asphalt demonstrates superior anti-rutting performance compared to the 50# asphalt. Furthermore, the rutting factor and fatigue factor of the 30# asphalt during aging are significantly higher than those of the 50# asphalt. With increasing temperature, stress level, and stress action time, the strain of the asphalt gradually increases. The unrecoverable creep compliance of the 50# asphalt exceeds that of the 30#. Although the high-temperature performance of the 30# asphalt mixture outperforms that of the 50# asphalt mixture, it exhibits lower flexural tensile strength and deformation ability at low temperatures compared to the 50# asphalt mixture. Overall, low-grade asphalt demonstrates relatively stable stress variations and exhibits good high-temperature stability.

Deer and sheep spines are often used as models of the human spine. A prerequisite for the use of animal models is information regarding the interspecies differences in the parameters of general interest. This would clarify the limitations of each animal model and substantiate the applicability of the obtained results to humans. Since sufficient data appear to be currently unavailable, we sought to investigate the feasibility of using deer and sheep as animal models for studies on the human spine. The objective of this study was a thorough comparison of the anatomical parameters of deer and sheep spines with those of the human spine. We employed three-dimensional reconstructions of computed tomography images, generated using figure analysis software, which facilitated quantitative analysis of the linear and curvature parameters and the geometric index of the vertebral bodies. Our findings represent a comprehensive database of the anatomical characteristics of the deer and sheep lumbar spines and their comparisons with those of the human lumbar spine. This study provides insight into the similarities and differences in the vertebral geometries between the human spine and the deer and sheep spines. We found that the differences are minimal and that they do not greatly compromise the utility of deer and sheep lumbar spines as models of the human lumbar spine.

La columna vertebral de ciervos y ovejas se utiliza frecuentemente como modelo de la columna vertebral humana. Un requisito previo para el uso de modelos animales es la información con respecto a las diferencias entre especies en los parámetros de interés general, lo que aclara las limitaciones de cada modelo animal y fundamenta la aplicabilidad de los resultados obtenidos para los seres humanos. Debido a que existen datos suficientes actualmente, hemos intentado investigar la viabilidad de utilizar ciervos y ovejas como modelos animales para los estudios sobre la columna vertebral humana. El objetivo fue realizar una comparación exhaustiva de los parámetros anatómicos de las columnas de ciervos y ovejas, con los de la columna vertebral humana. Empleamos reconstrucciones tridimensionales de imágenes de tomografía computadorizada, mediante un programa de análisis de la figura, lo que facilitó el análisis cuantitativo de los parámetros lineales y de la curvatura y el índice geométrico de las vértebras. Nuestros hallazgos representan una amplia base de datos de las características anatómicas de la columna lumbar de los ciervos y ovejas y sus comparaciones con las de la columna lumbar humana. Este estudio proporciona información sobre las similitudes y diferencias en las geometrías vertebrales entre la columna vertebral humana y las columnas de venado y oveja. Se encontró que las diferencias son mínimas y que no comprometen el uso de la columna de ciervos y ovejas como modelos de la columna lumbar humana.